Water-Filled Windows

Could water-filled windows cool and heat buildings more sustainably?

The WFG technology is being tested on prototype buildings located in Taiwan (pictured).

When it comes to keeping buildings energy efficient, windows certainly pose a challenge. It was with this quandary in mind that a British scientist has created a new type of window - one that's filled with water.

Due to the thermal shortcomings of glass, windows can significantly undermine the sustainability of a building. Most conventional windows allow heat to escape during cold days, thus increasing heating costs. On the other hand, during hot weather glass allows sunlight to stream in, thereby driving up the use of energy-guzzling air conditioning, according to New Atlas.

In an effort to overcome these inherent seasonal limitations, Dr. Matyas Gutai, an architecture lecturer at Loughborough University, has created a new type of window - one that’s filled with water.

Each “water-filled glass” (WFG) window contains a vertical sheet of water, sealed between two sheets of glass. As sunlight passes through the glass, it heats the water, thus keeping the room itself from getting as hot as it would otherwise.

Once it reaches a high enough temperature, that sun-warmed water is pumped out of the window, traveling through pipes in the wall to a storage tank elsewhere in the building. Cooler water is simultaneously pumped into the WFG, to replace that which was pumped out. When the outdoor temperature drops, later on, the stored warm water is pumped back out of the tank and into the pipes, warming the room by radiating heat through the walls.

Alternatively, warm water can also be used in the building’s taps, reducing the need to run the water heater.

Although some electricity is required to pump the water back and forth, computer simulations have shown that a WFG-equipped building would use up to 72 percent less energy compared to one with traditional heating systems.

“Glass is currently a liability in buildings as it compromises energy consumption, thermal comfort, acoustics, and other aspects,” says Gutai. “WFG changes this paradigm and turns glass into an opportunity for sustainable construction. It shows us that thinking holistically about buildings and building components leads to a more efficient and sustainable built environment.”